That you will need to figure out for yourself. You may want to speak with your doctor about what they think.
I read a lot about what dosage different people took for different situations. Most indicated something between 200 and 600 per day. Others were 800 or more milligrams per day.
I started out with 200 mg per day. I gradually added to that and eventually I ended up taking 1200 mg per day (600 morning and evening). This seemed to maximize the effect and I did not see any difference beyond that.
I took that amount for about three years. I’m no longer taking it, but I am considering resuming with it. The only reason I quit was I had more new expenses show up, my neuropathy was much improved and I just could not afford to keep taking it at the time.